Back in the 40's and 50's when you bought a pickup it came with a wood floor. It was always pine. This was not because pine was the best but because it was cheap.
Owners normally replaced the pine with oak when the pine wore out, but I knew a lot of people back then that replaced it with cedar.
None of it lasted, and when steel beds became available that was what people bought. But if you wanted a truck and just a truck you could get one with a wood floor. A heater, oil filter and spare tire were all optional.